IE Efficiency Classes
IE1–IE4 efficiency values and EU regulation compliance requirements.
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Electric Motor Products
IE3 standard efficiency, IE4 super premium efficiency, ATEX explosion-proof, and custom-duty motors — plus VFDs and soft starters. Specifications, EU regulations, and what to specify.
Buyer's guide — key specifications
To specify an electric motor: (1) Power (kW) and speed (poles: 2P=~2,900 RPM, 4P=~1,450 RPM, 6P=~960 RPM, 8P=~720 RPM); (2) Frame size (IEC: 56–450M — determines mounting dimensions); (3) Efficiency class (IE3 mandatory in EU for 0.75–1,000 kW as of July 2023; IE4 recommended for high-duty-cycle applications); (4) Enclosure (IP55 standard; IP65 for washdown; TEFC for most industrial); (5) Voltage and frequency (400V/50Hz standard EU); (6) Duty rating (S1 continuous; S3 intermittent — specify if <100% duty cycle); (7) Insulation class (Class F insulation standard; Class B temperature rise — the "F/B" standard for motors).
Efficiency Class Selection
| Efficiency class | EU regulation status | Typical efficiency (4-pole, 400V, 50Hz) | When to specify |
|---|---|---|---|
| IE2 (High) | No longer compliant for 0.75–1,000 kW without VFD in EU | 87–93% (7.5–75 kW range) | Only with VFD where regulation permits; or outside EU |
| IE3 (Premium) | Mandatory in EU for 0.75–1,000 kW (July 2021 onward) | 89–95% (7.5–75 kW range) | Standard specification for all new EU motor installations |
| IE4 (Super Premium) | Voluntary; mandatory for some sizes from 2023 | 90–96% (7.5–75 kW range) | High duty cycle (>6,000 hours/year); payback typically 1–3 years vs IE3 |
| IE5 (Ultra Premium) | Emerging — synchronous reluctance + VFD | 91–97% | Very high duty cycle; premium technology (SynRM motors) |
Motor Types and Enclosures
| Type | IP rating | Description | Application |
|---|---|---|---|
| TEFC (Totally Enclosed Fan Cooled) | IP55 | Standard industrial motor — enclosed housing, external fan cooling. Most common type | General industrial: pumps, fans, conveyors, compressors |
| TEFC Washdown | IP65–IP66 | Improved sealing; stainless steel hardware; food-grade paint | Food and beverage, pharmaceutical, washdown areas |
| TEFC High Efficiency | IP55 | IE3/IE4 motor with optimised copper windings and laminations | High duty cycle applications where energy cost justifies premium |
| ATEX Ex ec IIC (Zone 1/2) | IP55–IP65 | Explosion-proof certified to ATEX/IECEx — for use in explosive gas atmospheres | Chemical plants, refineries, offshore, paint booths, fuel handling |
| ATEX Ex tb IIIC (Zone 21/22) | IP65 | Dust explosion protection — for grain, flour, wood dust, coal dust environments | Mills, silos, woodworking, coal handling |
| Brake motor | IP55 | Integrated electromagnetic brake — fast stopping; holding torque when de-energised | Hoists, conveyors requiring load holding, positioning applications |
| Geared motor | IP55–IP65 | Motor + integral gearbox in one unit — helical, bevel-helical, or worm reduction | Conveyors, mixers, agitators, slow-speed drives |
Variable Frequency Drives (VFDs)
VFDs (also called inverters or VSDs) control motor speed by varying supply frequency. Key selection parameters:
- Rated output current (A): Must exceed motor full-load current with margin for starting torque. Standard duty = 110% overload for 60 s. Heavy duty = 150% overload for 60 s (for high inertia or frequent starting)
- Switching frequency (kHz): Higher switching frequency = lower motor noise but higher VFD losses and longer cable limits. Typically 4–16 kHz
- Input supply: Single-phase input up to ~2.2 kW; three-phase for larger. Check harmonic levels — EN 61000-3-12 compliance and whether line reactors or filters are needed
- Motor cable length: Long cables (>50 m) create voltage spikes that damage motor insulation — specify VFD-duty motor (Class F insulation + additional surge protection) and output reactor for cables >100 m
- Enclosure: IP20 for clean panel mounting; IP54/IP65 for standalone installation in dirty or wet environments
Soft Starters
Soft starters reduce starting current and torque by ramping up voltage during start. Unlike VFDs, they do not vary speed during running. Use when: starting current reduction is the goal (not speed control); application runs at a fixed speed; cost is a constraint. Not suitable where variable speed operation is needed. Key specifications: voltage, motor full-load current, starter continuous current rating, bypass contactor (internal or external).